title: Note: optical optimization for ultrasensitive photon mapping with submolecular resolution by scanning tunneling microscope induced luminescence.
abstract: We report the development of a custom scanning tunneling microscope equipped with photon collection and detection systems. The optical optimization includes the comprehensive design of aspherical lens for light collimation and condensing, the sophisticated piezo stages for in situ lens adjustment inside ultrahigh vacuum, and the fiber-free coupling of collected photons directly onto the ultrasensitive single-photon detectors. We also demonstrate submolecular photon mapping for the molecular islands of porphyrin on Ag(111) under small tunneling currents down to 10 pA and short exposure time down to 1.2 ms/pixel. A high quantum efficiency up to 10(-2) was also observed.
authors.affiliation: HFNL, University of Science and Technology of China, Hefei, Anhui 230026, China.
authors.forename: L G
authors.initials: LG
authors.lastname: Chen
authors.forename: C
authors.initials: C
authors.lastname: Zhang
authors.forename: R
authors.initials: R
authors.lastname: Zhang
authors.forename: X L
authors.initials: XL
authors.lastname: Zhang
authors.forename: Z C
authors.initials: ZC
authors.lastname: Dong